﻿using Microsoft.Extensions.Caching.Memory;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text.RegularExpressions;

namespace WaterCloud.Code
{
	/// <summary>
	/// 缓存帮助类
	/// </summary>
	public class MemoryCacheHelper
	{
		private static readonly MemoryCache Cache = new MemoryCache(new MemoryCacheOptions());

		/// <summary>
		/// 验证缓存项是否存在
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <returns></returns>
		public static bool Exists(string key)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));
			return Cache.TryGetValue(key, out _);
		}

		/// <summary>
		/// 添加缓存
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <param name="value">缓存Value</param>
		/// <param name="expiresSliding">滑动过期时长（如果在过期时间内有操作，则以当前时间点延长过期时间）</param>
		/// <param name="expiressAbsoulte">绝对过期时长</param>
		/// <returns></returns>
		public static bool Set(string key, object value, TimeSpan expiresSliding, TimeSpan expiressAbsoulte)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));
			if (value == null)
				throw new ArgumentNullException(nameof(value));

			Cache.Set(key, value.ToJson(),
				new MemoryCacheEntryOptions().SetSlidingExpiration(expiresSliding)
					.SetAbsoluteExpiration(expiressAbsoulte));
			return Exists(key);
		}

		/// <summary>
		/// 添加缓存
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <param name="value">缓存Value</param>
		/// <param name="expiresIn">缓存时长</param>
		/// <param name="isSliding">是否滑动过期（如果在过期时间内有操作，则以当前时间点延长过期时间）</param>
		/// <returns></returns>
		public static bool Set(string key, object value, TimeSpan expiresIn, bool isSliding = false)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));
			if (value == null)
				throw new ArgumentNullException(nameof(value));
			Cache.Set(key, value.ToJson(),
				isSliding
					? new MemoryCacheEntryOptions().SetSlidingExpiration(expiresIn)
					: new MemoryCacheEntryOptions().SetAbsoluteExpiration(expiresIn));

			return Exists(key);
		}

		/// <summary>
		/// 添加缓存
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <param name="value">缓存Value</param>
		/// <returns></returns>
		public static bool Set(string key, object value)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));
			if (value == null)
				throw new ArgumentNullException(nameof(value));
			Cache.Set(key, value.ToJson());

			return Exists(key);
		}

		#region 删除缓存

		/// <summary>
		/// 删除缓存
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <returns></returns>
		public static void Remove(string key)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));

			Cache.Remove(key);
		}

		/// <summary>
		/// 批量删除缓存
		/// </summary>
		/// <returns></returns>
		public static void RemoveAll(IEnumerable<string> keys)
		{
			if (keys == null)
				throw new ArgumentNullException(nameof(keys));

			keys.ToList().ForEach(item => Cache.Remove(item));
		}

		#endregion 删除缓存

		#region 获取缓存

		/// <summary>
		/// 获取缓存
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <returns></returns>
		public static T Get<T>(string key)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));
			object temp;
			if (Cache.TryGetValue(key, out temp))
			{
				return temp.ToString().ToObject<T>();
			}
			return default(T);
		}

		/// <summary>
		/// 获取缓存
		/// </summary>
		/// <param name="key">缓存Key</param>
		/// <returns></returns>
		public static string Get(string key)
		{
			if (key == null)
				throw new ArgumentNullException(nameof(key));
			if (Cache.Get(key) == null)
			{
				return string.Empty;
			}
			return Cache.Get(key).ToString();
		}

		/// <summary>
		/// 获取缓存集合
		/// </summary>
		/// <param name="keys">缓存Key集合</param>
		/// <returns></returns>
		public static IDictionary<string, object> GetAll(IEnumerable<string> keys)
		{
			if (keys == null)
				throw new ArgumentNullException(nameof(keys));

			var dict = new Dictionary<string, object>();
			keys.ToList().ForEach(item => dict.Add(item, Cache.Get(item)));
			return dict;
		}

		#endregion 获取缓存

		/// <summary>
		/// 删除所有缓存
		/// </summary>
		public static void RemoveCacheAll()
		{
			var l = GetCacheKeys();
			foreach (var s in l)
			{
				Remove(s);
			}
		}

		/// <summary>
		/// 删除匹配到的缓存
		/// </summary>
		/// <param name="pattern"></param>
		/// <returns></returns>
		public static void RemoveCacheRegex(string pattern)
		{
			IEnumerable<string> l = SearchCacheRegex(pattern);
			foreach (var s in l)
			{
				Remove(s);
			}
		}

		/// <summary>
		/// 搜索 匹配到的缓存
		/// </summary>
		/// <param name="pattern"></param>
		/// <returns></returns>
		public static IEnumerable<string> SearchCacheRegex(string pattern)
		{
			var cacheKeys = GetCacheKeys();
			var l = cacheKeys.Where(k => Regex.IsMatch(k, pattern)).ToList();
			return l.AsReadOnly();
		}

		/// <summary>
		/// 获取所有缓存键
		/// </summary>
		/// <returns></returns>
		public static List<string> GetCacheKeys()
		{
#if NET8_0
            const BindingFlags flags = BindingFlags.Instance | BindingFlags.NonPublic;
            var entries = Cache.GetType().GetField("_coherentState", flags)?.GetValue(Cache);
            var cacheItems = entries?.GetType().GetProperty("EntriesCollection", flags).GetValue(entries) as ICollection; //entries as IDictionary;
            var keys = new List<string>();
            if (cacheItems == null) return keys;
            foreach (var item in cacheItems)
            {
                var methodInfo = item.GetType().GetProperty("Key");

                var val = methodInfo.GetValue(item);

                keys.Add(val.ToString());
            }
            return keys;
#else
            const BindingFlags flags = BindingFlags.Instance | BindingFlags.NonPublic;
            var entries = Cache.GetType().GetField("_entries", flags).GetValue(Cache);
            var cacheItems = entries as IDictionary;
            var keys = new List<string>();
            if (cacheItems == null) return keys;
            foreach (DictionaryEntry cacheItem in cacheItems)
            {
                keys.Add(cacheItem.Key.ToString());
            }
            return keys;
#endif
        }
    }
}